How to set HBook so customers send booking requests that need to be confirmed?

You can set HBook as a booking request system. A customer will send a booking enquiry and you will be able to approve or decline their request.

• If you wish to treat only one request at a time for a same period
  In HBook->Misc->Confirmation settings, you will keep the default configuration, where dates are blocked out in the calendar automatically when a request is received.
  

• If you wish to receive various requests for a same period and decide which one you accept
  In HBook->Misc->Confirmation settings, you will set that a reservation needs to be confirmed before dates are blocked out in the calendar.

In HBook->Text, you can change any front-end text displayed by HBook on your website, so you adapt the text for a booking request system, for example replacing "Book now" by "Send us a booking request'. 

In HBook->Emails, You can set email templates to be sent on "New reservation/request", "Reservation confirmation" and "Reservation cancellation". You can set as many email templates as you wish for each action (for the customer, the admin, ...).

This way, you and the customer can be notified of the reception of a new request, on "New reservation". You can confirm the reservation request from the back-end and have a confirmation email sent to the guest, or you can decline the reservation request and have as well an automatic email sent to the customer.

• If you are using Stripe payment gateway
  In HBook->Payment ->Booking payment settings, you might wish to set that "Customer have to leave their credit card details". And in HBook->Payment ->Stripe settings, you will enable "Store credit card".
  By doing so, you can charge the card directly from the reservation list once you have approved the reservation. The transaction is done through Stripe, even though you manage it directly in HBook reservation list dashboard.
  

• If you are not using Stripe payment gateway or if you do not wish to ask for credit card details
  In HBook->Payment ->Booking payment settings, you will set that "Customers do not have to pay online to book". You can include payment instructions in the automatic email that will be sent out when you approve the booking request.